1 #ifndef _LINUX_GENERIC_RADIX_TREE_H 2 #define _LINUX_GENERIC_RADIX_TREE_H 3 4 /** 5 * DOC: Generic radix trees/sparse arrays 6 * 7 * Very simple and minimalistic, supporting arbitrary size entries up to 8 * PAGE_SIZE. 9 * 10 * A genradix is defined with the type it will store, like so: 11 * 12 * static GENRADIX(struct foo) foo_genradix; 13 * 14 * The main operations are: 15 * 16 * - genradix_init(radix) - initialize an empty genradix 17 * 18 * - genradix_free(radix) - free all memory owned by the genradix and 19 * reinitialize it 20 * 21 * - genradix_ptr(radix, idx) - gets a pointer to the entry at idx, returning 22 * NULL if that entry does not exist 23 * 24 * - genradix_ptr_alloc(radix, idx, gfp) - gets a pointer to an entry, 25 * allocating it if necessary 26 * 27 * - genradix_for_each(radix, iter, p) - iterate over each entry in a genradix 28 * 29 * The radix tree allocates one page of entries at a time, so entries may exist 30 * that were never explicitly allocated - they will be initialized to all 31 * zeroes. 32 * 33 * Internally, a genradix is just a radix tree of pages, and indexing works in 34 * terms of byte offsets. The wrappers in this header file use sizeof on the 35 * type the radix contains to calculate a byte offset from the index - see 36 * __idx_to_offset. 37 */ 38 39 #include <asm/page.h> 40 #include <linux/bug.h> 41 #include <linux/log2.h> 42 #include <linux/math.h> 43 #include <linux/types.h> 44 45 struct genradix_root; 46 47 struct __genradix { 48 struct genradix_root *root; 49 }; 50 51 /* 52 * NOTE: currently, sizeof(_type) must not be larger than PAGE_SIZE: 53 */ 54 55 #define __GENRADIX_INITIALIZER \ 56 { \ 57 .tree = { \ 58 .root = NULL, \ 59 } \ 60 } 61 62 /* 63 * We use a 0 size array to stash the type we're storing without taking any 64 * space at runtime - then the various accessor macros can use typeof() to get 65 * to it for casts/sizeof - we also force the alignment so that storing a type 66 * with a ridiculous alignment doesn't blow up the alignment or size of the 67 * genradix. 68 */ 69 70 #define GENRADIX(_type) \ 71 struct { \ 72 struct __genradix tree; \ 73 _type type[0] __aligned(1); \ 74 } 75 76 #define DEFINE_GENRADIX(_name, _type) \ 77 GENRADIX(_type) _name = __GENRADIX_INITIALIZER 78 79 /** 80 * genradix_init - initialize a genradix 81 * @_radix: genradix to initialize 82 * 83 * Does not fail 84 */ 85 #define genradix_init(_radix) \ 86 do { \ 87 *(_radix) = (typeof(*_radix)) __GENRADIX_INITIALIZER; \ 88 } while (0) 89 90 void __genradix_free(struct __genradix *); 91 92 /** 93 * genradix_free: free all memory owned by a genradix 94 * @_radix: the genradix to free 95 * 96 * After freeing, @_radix will be reinitialized and empty 97 */ 98 #define genradix_free(_radix) __genradix_free(&(_radix)->tree) 99 100 static inline size_t __idx_to_offset(size_t idx, size_t obj_size) 101 { 102 if (__builtin_constant_p(obj_size)) 103 BUILD_BUG_ON(obj_size > PAGE_SIZE); 104 else 105 BUG_ON(obj_size > PAGE_SIZE); 106 107 if (!is_power_of_2(obj_size)) { 108 size_t objs_per_page = PAGE_SIZE / obj_size; 109 110 return (idx / objs_per_page) * PAGE_SIZE + 111 (idx % objs_per_page) * obj_size; 112 } else { 113 return idx * obj_size; 114 } 115 } 116 117 #define __genradix_cast(_radix) (typeof((_radix)->type[0]) *) 118 #define __genradix_obj_size(_radix) sizeof((_radix)->type[0]) 119 #define __genradix_idx_to_offset(_radix, _idx) \ 120 __idx_to_offset(_idx, __genradix_obj_size(_radix)) 121 122 void *__genradix_ptr(struct __genradix *, size_t); 123 124 /** 125 * genradix_ptr - get a pointer to a genradix entry 126 * @_radix: genradix to access 127 * @_idx: index to fetch 128 * 129 * Returns a pointer to entry at @_idx, or NULL if that entry does not exist. 130 */ 131 #define genradix_ptr(_radix, _idx) \ 132 (__genradix_cast(_radix) \ 133 __genradix_ptr(&(_radix)->tree, \ 134 __genradix_idx_to_offset(_radix, _idx))) 135 136 void *__genradix_ptr_alloc(struct __genradix *, size_t, gfp_t); 137 138 /** 139 * genradix_ptr_alloc - get a pointer to a genradix entry, allocating it 140 * if necessary 141 * @_radix: genradix to access 142 * @_idx: index to fetch 143 * @_gfp: gfp mask 144 * 145 * Returns a pointer to entry at @_idx, or NULL on allocation failure 146 */ 147 #define genradix_ptr_alloc(_radix, _idx, _gfp) \ 148 (__genradix_cast(_radix) \ 149 __genradix_ptr_alloc(&(_radix)->tree, \ 150 __genradix_idx_to_offset(_radix, _idx), \ 151 _gfp)) 152 153 struct genradix_iter { 154 size_t offset; 155 size_t pos; 156 }; 157 158 /** 159 * genradix_iter_init - initialize a genradix_iter 160 * @_radix: genradix that will be iterated over 161 * @_idx: index to start iterating from 162 */ 163 #define genradix_iter_init(_radix, _idx) \ 164 ((struct genradix_iter) { \ 165 .pos = (_idx), \ 166 .offset = __genradix_idx_to_offset((_radix), (_idx)),\ 167 }) 168 169 void *__genradix_iter_peek(struct genradix_iter *, struct __genradix *, size_t); 170 171 /** 172 * genradix_iter_peek - get first entry at or above iterator's current 173 * position 174 * @_iter: a genradix_iter 175 * @_radix: genradix being iterated over 176 * 177 * If no more entries exist at or above @_iter's current position, returns NULL 178 */ 179 #define genradix_iter_peek(_iter, _radix) \ 180 (__genradix_cast(_radix) \ 181 __genradix_iter_peek(_iter, &(_radix)->tree, \ 182 PAGE_SIZE / __genradix_obj_size(_radix))) 183 184 static inline void __genradix_iter_advance(struct genradix_iter *iter, 185 size_t obj_size) 186 { 187 iter->offset += obj_size; 188 189 if (!is_power_of_2(obj_size) && 190 (iter->offset & (PAGE_SIZE - 1)) + obj_size > PAGE_SIZE) 191 iter->offset = round_up(iter->offset, PAGE_SIZE); 192 193 iter->pos++; 194 } 195 196 #define genradix_iter_advance(_iter, _radix) \ 197 __genradix_iter_advance(_iter, __genradix_obj_size(_radix)) 198 199 #define genradix_for_each_from(_radix, _iter, _p, _start) \ 200 for (_iter = genradix_iter_init(_radix, _start); \ 201 (_p = genradix_iter_peek(&_iter, _radix)) != NULL; \ 202 genradix_iter_advance(&_iter, _radix)) 203 204 /** 205 * genradix_for_each - iterate over entry in a genradix 206 * @_radix: genradix to iterate over 207 * @_iter: a genradix_iter to track current position 208 * @_p: pointer to genradix entry type 209 * 210 * On every iteration, @_p will point to the current entry, and @_iter.pos 211 * will be the current entry's index. 212 */ 213 #define genradix_for_each(_radix, _iter, _p) \ 214 genradix_for_each_from(_radix, _iter, _p, 0) 215 216 int __genradix_prealloc(struct __genradix *, size_t, gfp_t); 217 218 /** 219 * genradix_prealloc - preallocate entries in a generic radix tree 220 * @_radix: genradix to preallocate 221 * @_nr: number of entries to preallocate 222 * @_gfp: gfp mask 223 * 224 * Returns 0 on success, -ENOMEM on failure 225 */ 226 #define genradix_prealloc(_radix, _nr, _gfp) \ 227 __genradix_prealloc(&(_radix)->tree, \ 228 __genradix_idx_to_offset(_radix, _nr + 1),\ 229 _gfp) 230 231 232 #endif /* _LINUX_GENERIC_RADIX_TREE_H */ 233